Whilst all the above is true, the Florida Street anecdote is just illustrative of how normal it is. Living in Recoleta, you will quickly discover discreet businesses (often an office where people pay their utility bills) that you simply enter and, instead of paying a bill, buy pesos in a booth with a counting machine and complete privacy at the prevailing rate (that hour). No dealing with shady-looking characters on a major pedestrian street and then following him down an alley, as happens in Florida Street.
(Two hundred dollars is a lot of money here, but doesnt go as far as it used to. For two people, you might you need to change larger amounts if you are to avoid having to go back every few days.)